Front edge detector mechanism



1950 H. T. BACKHOUSE FRONT EDGE DETECTOR MECHANISM Filed Aug. 10, 1948 JNVEN TOR. Ham 5y 7bw/vsavaflAcA 6'ww BY flaw 7 2M? A T TO R N E Y6 Patented Feb. 28, 1950 room EDGE DETECTOR MECHANISM Headley Townsend Backhouse, Wentworth,

. England Application August 10, 1948, Serial No. 43,427 In Great Britain August 5, 194-7 4 Claims. (Cl. 271i56) This invention comprises improvements in or relating tofront edge detector mechanismfor. use in sheet feeding apparatus. The invention isconcerned with sheet feeding apparatus. of the kind in which sheets of paper or the: like are removed in succession from a pile and: fed on to a layboard where, by means of lays or the equivalent, registration of the sheets: is effected before they are transferred to a printing or other machine.

In one form of such. apparatus with which the invention is.- particularly, but not exclusively, concerned the sheets approach the lay-board in a continuous stream of partly overlapping sheets. Sheet feeding apparatus of. this form. are commonly known as stream-feeders. The invention comprises. a feelermovably supported in the path of the sheets at or near the front lays and arranged for movement by each sheet in turn as the sheet approachesor reaches the front lays; and sensing mechanism operated in timed relationship with the sheetfeeding. mechanism. for determining whether or not the feeler has been .moved as aforesaid by a. correctly placed sheet.

In. the preferred form: of the mechanism the sensing mechanism is arranged,.'on sensing that the feeler has not been moved, for causing: stoppage of the feeding of the sheetsand/or the operation of a warning device.

It is an object of the present invention to improve the mechanism described' in respect of. the

adaptability of the mechanism. to sheetefee'ding machines of varying dimensions.

The invention provides detector mechanism in which the f'eeler is carried on. one-end .of asupporting arm which is attached at its other end to a fixed support member and is variable in eifectivelength (by a simple adjustment such: as a sliding movement controlled by athumb-screw) to enable the mechanism to be. fitted to sheet feeding apparatus of different constructions and having, lay-boards of different dimensions;

Preferably, thev supporting arm. is pivotally' attached. to the: support member: for partial. rotation about a. transverse horizontalaids and means are: provided for rocking the; supporting: arm in timed relationship with the sheet feeding ma.- chine to lift. the feeler upwardly from. the layboard to facilitate" removal. of each. registered sheet, in turn and then to return; the feeler to: the initial position to detect the arrival. of the next sheet. The. rocking means may comprise a follower on the supportingarm cor-operating with a swinging, cam surface on the aforesaid sensing mechanism T 1 The sensing mechanism may comprise an arm or the equivalent. operated in timed relationship with the feeding of the sheets in combination with trip mechanism having a stop presented for possible engagement by the sensing arm during each. forward movement thereof and on such engagement to restrict further movement of the arm but arranged tobe Withdrawn from said path on each movement of the feeler as aforesaid, the operation of the sensing mechanism being, so timed that each sheet as it arrives at or approaches the lays in proper sequence causes the stop to be withdrawnbefore engagement with the sensing arm, but should a sheetbe. delayed or fail to feed the stop will engage the arm and causethe stoppage of the. feeder or the operation of the warning device. When the invention is applied to the form of detector mechanism illustrated herein the trip mechanism may comprise a rotatably mounted shaft which is extensible in length and which is spring-urged for rotation about its major axis from. a stop position in which a radial projection from the shaft constituting the stop, lies in the path of the sensing arm and theshaft is retained in the stop position b the f'eeler or a part controlled by the feeler, until the feeler is moved by a sheet, whereby unless such movement of the feeler occurs at theappropriate time the stop engages and. stops the: sensing arm. Preferably, the shaft incorporates a torsionally locked telescopic joint, in order that it may be extensible. The feeler may comprise a pivoted arm arranged to be moved about its pivot'by the sheets: as they approach or reach the front lays and to constitute a latch securing a rocker which controls the spring-urged rotation of the shaft, the construction and arrangement being such that when the feeler is moved by a. correctly placed sheet thev rocker is released and allows the shaft to rotate towithdraw the stop from the path of the moving arm. The. mecha. nism may include a resetting device eperable to reset the shaft into the stop position between the feeding of successive sheets, and. comprising a bell-crank of which one arm is arranged. for. engagement by the sensing arm near the end of the backward stroke thereof. and the bell-crank. is

thereby given amovement of rotation about its pivot and the other arm is: arranged on such. rotation, to engage a cam; or equivalent, surface on the shaft and thereby to rotate the shaft into I the stop position.

example and with reference to the accompanying drawings in which--- 7 screw which is housed in the bracket I. forward end of the tube l8 houses'a feeler 26 normally suspended in a vertical position by a pivot pin 21, and a rocker 24 pivoted on a pin 25. A leaf spring 28 lightly urges the feeler 26 against Fig. 1 represents diagrammatically a perspective view partly in section, of the mechanism before engagement of the feeler by a sheet, and

Fig. 2 represents diagrammatically a perspective view of a part of the mechanism, partly in section, in which the feeler has been engaged by a correctly placed sheet.

The example of the mechanism shown in the drawings is intended for use in a stream-feeder which feeds the sheets in partly overlapped formation on to a lay-board 33, having front lays 34 which, during the registration period, extend above the board to provide registration stops. The mechanism comprises a bracket i slidably mounted on a angle cross-bar 2 attached at its ends to the frame (not shown) and secured to said cross-bar by a clamping screw 3. The bracket has a rearward extension which is forked and embraces an oscillating shaft 32 to which is keyed a sensing arm 4.

A forward extension of said bracket carries ,on a pivot M a member I! of inverted channel shape in which is slidably fitted a rectangular tube 18 which is slotted at 36 to receive a clamping screw 31 having a nut Hi; the channel-shaped member I! and the rectangular tube it; together forming a pivoted extensible arm, A compression spring l5 depresses the forward end of this pivoted arm and causes an upward extension 35 on the rear of said arm to abut against a stop The an abutment l8b (shown in Fig. 2) formed by suitably cutting away the bottom wall of the tube I8. A hearing 23 is fixed in the tube l8 behind the rear end of the rocker 24 and a short shaft 22 which has a D-shaped head is journaled in said bearing and held against longitudinal displacement by means of a pin 29, and the flaton the D-shaped head is arranged to cooperate with. the rear end of the rocker 24 in such a manner that rotation of the shaft 22 from the position shown in Fig. 1 will lift the rear end of the rocker. A square rod 20, fixed to the shaft 22,

extends to the rear and is slidable in a square tube I9, the other end of which is fixed in a hollow shaft i I rotatable in a bearing i3. A spiral spring 2! is secured at its inner end to the forward end of the rod 20. The outer end of the spring is secured to and reacts against one wall of the tube [8 thus tending to rotate parts H, I9, and 22 clockwise as viewed in the draw- At the rear end of the channel If the web is cut away leaving the two sides between which is mounted a bell-crank lever i pivoted on a pin 8. An adjusting screw 6 is fitted to the upward- -ly extending arm of the lever l and is arranged to abut against the rear face of a cam and stop piece H! which is fixed to the arm 4. The horizontal arm of the bell-crank lever I has a fiat upper surface arranged to cooperate with a flat on the rotatable shaft H and has its downward travel limited by a pin 9 secured to the sides of the channel H. A pin l2 extends radially from the shaft H and is arranged to stop the forward motion of the cam and stop piece Ill when the shaft 22 is in the position shown in Fig. l (i. e.

if the feeler has not been moved by a correctly placed sheet). When the sensing arm 4 and the stop and cam piece It are at the rearward limit of their travel the screw 6 is adjusted so that there is a slight clearance between the feeler 26 and the front end of the rocker 24, the rear end of said rocker being heavier than its front end. The feeler is therefore free to be moved by a correctly advanced sheet against the light pressure exerted on it by the leaf-spring 28 and without interference by the rocker.

The operation of the mechanism shown in Figs. 1 and 2 is as follows:

Starting from the Fig. 1 position when the feeler is moved forward by a correctly advanced sheet the abutment on its upper end is moved from under the forward end of the rocker 24, the leaf spring 28 yielding sufficiently to permit this action. The sensing arm 4 carrying the cam and stop piece l0 then moves forward thereby allowing the lever to move and consequently allowing parts H, [9, 20 and 22 partly to rotate under the action of the spring 2!. By this rotation the pin l2, which has until this time been in the path of the stop piece on the cam I9, is moved out of said path and the rear end of the rocker 24 is lifted by the D-shaped head of shaft 22, so depressing the front end of the rocker and lifting the feeler above the path of the sheet in the manner illustrated in Fig. 2. Spring 28 is thereby placed under stress. The cam 10 continues to move forward and engages the roller 30 (supported by pin 3! in bearings in container thereby depressing the rear end of the member I! on which said roller is mounted and causing its front end, together with all the parts mounted on it to the fore of the pivot l4, to be lifted further from the sheet.

In the event of a sheet arriving late in the stream of sheets the feeler 26 is not moved to release the rocker 24 and parts 22, 28, I9 and H before the sensing arm 4 in its forward movement brings the stop piece [9 into engagement with pin l2 which arrests further movement of the arm l0 and causes the mechanism to stop by known means.

As the sensing arm 4 swings rearward the pressure of cam l0 against follower 38 is relieved and spring l5 lowers the forward end of channel I1. Immediately thereafter bell crank i is turned clockwise and through its camming action on the part if shaft I9, 22 is rocked back to the Fig. 1 position, whereupon spring 28 acts to snap a rocker 24 and feeler 26 to their original positions shown in Fig. 1. The full tension of spring 2! is thereby restored and the parts are ready for the next cycle.

Having thus described my invention, I claim:

1. In sheet feeding apparatus of the kind described, a fixed support, an extensible sup-porting arm mounted upon and projecting forwardly from said fixed support, a feeler at the forward extremity of said supporting arm, a transverse J oscillating shaft associated with said fixed support, a sensing arm fixed on said shaft, means carried by said supporting arm and comprising an element extending lengthwise of the arm and controlled by said feeler for stopping motion of said sensing armand its shaft when the feeder fails to present a properly fed sheet to said feeler at the correct time in the cycle, and'means for determining the effective length of said lengthwise element to correspond with different adjustments of said extensible support arm.

2. Apparatus as defined in claim 1, wherein said supporting arm is carried by a transverse pivot mounted on said fixed support and comprising means actuated by the oscillations of said sensing arm for swinging said supporting arm on its pivot to lift said feeler above the sheet path during a portion of each cycle in which a properly fed sheet is presented to the feeler.

3. Apparatus as defined in claim 2, wherein the means for swinging said supporting arm comprises a follower on the supporting arm cooperating With a cam surface on the aforesaid sensing arm.

4. In sheet feeding apparatus of the kind described, a fixed support, an extensible supporting arm mounted upon and projecting forwardly from said fixed support, a feeler at the forwardextremity of said supporting arm, a transverse oscillating shaft associated with. said fixed support, a sensing arm fixed on said shaft, an extensible shaft rotatably mounted in said supporting arm and extending longitudinally thereof, said extensible shaft having a stop projection adapted to stand in the path of said sensing arm, means controlled by said feeler for holding said projection in said path except when the feeler is tripped by a properly fed sheet, spring means functioning when said feeler is tripped for rotating said extensible shaft to remove said stop projection from the path of said sensing arm, and means actuated by the oscillations of said sensing arm in one direction for turning said extensible shaft to return said stop projection to the path of said sensing arm and to put said spring means under tension.

HEADLEY TOWNSEND BACKHOU'SE.

REFERENCES CITED UNITED STATES PATENTS Name Date I-Iarrold Dec. 23, 1947 Number 

